<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<script src="js/jquery-3.4.1.min.js"></script>
	</head>
	<body>
		<select name="province">
			<option value="1">江苏省</option>
			<option value="2">浙江省</option>
		</select>
		<select name="city">
			<option value="1-1">南京</option>
			<option value="1-2">苏州</option>
			<option value="1-3">杨州</option>
		</select>

		<script>
			$(function() {
				$("[name=province]").on("change", function() {
					var pro = $(this).val();
					var $city=$("[name=city]");
					switch (pro) {

						case "1":
							$city.empty();
							$city.append("<option value='1-1'>南京</option>");
							$city.append("<option value='1-2'>苏州</option>");
							$city.append("<option value='1-3'>杨州</option>");
							break;

						case "2":
							$city.empty();
							$city.append("<option value='2-1'>杭州</option>");
							$city.append("<option value='2-2'>义乌</option>");
							$city.append("<option value='2-3'>金华</option>");
							break;
					}
				})
			})
		</script>
	</body>
</html>
